Assessment of crustal thinning and tectonic stress distribution of Gülbahçe fault zone and its surroundings (İzmir, West Türkiye) using gravity and magnetic anomalies

Year 2022, , 105 - 119, 05.12.2022

Oya Pamukçu Ayça Çırmık Fikret Doğru Ece Ünlü Barış Can Malaliçi

https://doi.org/10.19111/bulletinofmre.1029265

Abstract

Gülbahçe Fault Zone (GFZ) is a significant tectonic structure and seismic source for İzmir city and its surroundings. The major earthquakes occurred at the surroundings of GFZ are 2005 Seferihisar, 2020 Samos Island-Aegean Sea and 2021 Seferihisar earthquakes. In this study, the crustal thinning and tectonic stress distribution of GFZ and its surroundings were analyzed by using the new gravity and magnetic data. The correspondence analysis was applied by appraising together the magnetic and free-air anomaly data. Moreover, the average density of the subsurface structure was calculated by applying the Parasnis method. The deviatoric stress calculation was executed and the change of the physical properties that controls the gravity and magnetic anomaly of the crustal structure of the GFZ and its surroundings from north to south was investigated. Therefore, the average density values, which were obtained from gravity anomalies, were computed as 2.59 gr / cm3 in the north of the study region and it decreased to 2.06, 1.8 and 1.49 gr / cm3 towards to the south. The freeair gravity anomaly values were between 0-70 mGal and the magnetic anomalies were between -450-150 nT. The deviatoric stress values were between -0.2-0.1 MPa.

Keywords

Bouguer Gravity Anomaly, Gülbahçe Fault Zone (GFZ), Magnetic, Microgravity, Parasnis Method.

Supporting Institution

In this study the microgravity and magnetic data of the projects (Project No: 2018.KB.FEN.010) funded by Dokuz Eylül University Scientific Research Project and The Scientific and the Technological Research Council of Turkey (TUBITAK) (Project No: 108Y285) were used.

Project Number

Project No: 2018.KB.FEN.010-Project No: 108Y285

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